The long-term outcome of aortocoronary vein bypass operation, in terms of histological changes in the vein grafts obtained at autopsy or revascularization, and return to gainful employment will be ascertained by a follow-up program of 2000 patients who had the operation over a 5-year period. The possible association of the graft lesions with the presence of the risk factors, such as history of smoking, hyperlipidemia or hypertension, will also be investigated.